1. Field of the Invention
This invention relates to spectrometers and, more particularly, to photoacoustic spectrometers.
2. Prior Art
The broad concept of analyzing substances through the use of photospectroscopy is quite old. For example, see the article Photoacoustic Spectroscopy of Solids written by Allan Rosencwaig and appearing in the magazine PHYSICS TODAY for September 1975. That article gives a good historical perspective of the technique and its advantages over destructive spectrographic techniques. It also distinguishes infra-red gas analyzers from photoacoustic U.S. Pat. No. 3,948,345 issued Apr. 6, 1976, to Allan Rosencwaig describes a commonly used technique. That technique involves irradiating a sample with radiant energy of variable frequency and detecting the resulting acoustical energy with a microphone. The problem with such a technique is that the microphone is sensitive to extraneous noises and other ambient conditions.
The problems of ultraviolet-visible absorption and reflectance spectrometry are well known.
Therefore, it is the general object of the present invention to overcome the problems and disadvantages experienced with prior art devices and methods.
It is a further object of this invention, to provide a material analyzing system and method which accurately gives information as to the nature of the material being analyzed.
It is a still further object of this invention to provide a method and apparatus for non-destructive analysis of non-gaseous materials of all kinds, including emulsions, solids and living organisms.